OEMTOOLS 27145 Combustion Leak Detector Locate Internal Combustion Leaks Quickly and Easily When Fluid Turns From BLUE to YELLOW Combustion Leak is Present Tests in seconds for: Blown Head Gasket (BHG) Cracked Head or Block Pulled Bolts or Studs Warped Sealing Surfaces Designed for Professional Auto Mechanics and Heavy duty Applications Comes in Sturdy Blow Molded Plastic Case